Set-point viral load and the basic reproductive number, , as a function of CTL-mediated killing.

<p>The left panels depict the behavior when killing is induced with a total rate per day. The viral load decreases sharply for d (A) since falls below one, and the infection is cleared (C). If CTL effector cells form a complex with the infected cell before delivering their lethal hit, we assume a maximal killing rate ( d) and change the Michaelis-Menten constant instead. This way, we can account for orders of magnitude differences in the viral load (B) since is slowly approaching one (solid line, D). The total killing (dashed line, D) induced by all CTL effector cells is approaching the same critical value around 5 d although d. In panel (A) and (B), the dotted line represents the usual detection limit for HIV-1. The dotted line in panel (C) and (D) depicts the of 1 below which the infection cannot sustain itself anymore.